1. The Field of the Invention
This invention relates to mechanical log splitters. More particularly, this invention relates to mechanical log splitters in which relative motion is imparted between a cleaving blade and a log longitudinal the axis thereof such that the log is split by the cleaving blade being forced thereinto.
2. The Background Art
Mechanical log splitters are known in which a log is split when a cleaving blade is forced into the log parallel to the longitudinal axis thereof because of relative motion imparted between the log and the cleaving blade by the log splitter. This relative motion may be created by either restraining the log to be split and mechanically driving the cleaving blade, or by forcing each log against and onto a cleaving blade that is fixed.
In either instance, however, a number of disadvantages afflict the known devices. Conventional cleaving blades take the form of upstanding plate-like knives or wedges. Many are by design extremely tall, so as to be at least equal to the diameter of the average log to be split. When such cleaving blades initially enter one end of a log, they impale it, thereby precluding rotation, and then proceed to sever the log along its length on a plane defined by the line of entry of the cleaving blade.
Unfortunately, this type of cleaving blade, no matter how sharply honed, fails to exploit the natural tendency of any given log to split along a line of least resistance, as when there are natural fracture lines in the log. Instead, such cleaving blades sever logs in a straight line without regard to tough spots, such as knots or burls, in a process which is more akin to cutting, than to splitting.
It has been observed that with the use of such conventional cleaving blades, the actual splitting of a log occurs within the early stages of initial penetration of the cleaving blade. Such splitting is often accompanied by a loud popping sound in the log within, for example, the first half inch of cleaving blade penetration. The remainder of the travel stroke of the log-splitting machinery involved merely spreads apart the already broken log, so that the power demand of the equipment is very uneven.
Nevertheless, it is frequently the case that the internal structure of the tough spots of a log in combination with its orientation on a mechanical splitter relative the plane of the cleaving blade do not lend themselves to such an initial split or break. Under these conditions, the log splitter must either drive the cleaving blade through the entire length of the log in a power-intensive slicing process, or become jammed. Once the log and cleaving blade are in contact, the plane upon which the two halves of the log will be separated is fixed. If this does not fortunitiously happen to closely coincide with a line of least resistance for splitting, a waste of energy and possibly jamming will result.
Furthermore, known devices using upstanding planar cleaving blades separate a log into two pieces of generally semicircular cross-section. Such pieces of wood are appropriate for use as firewood only if logs of relatively small diameter are used. Accordingly, the routine practice is to split in half each of these two pieces. This results in a log spit into quarters, but requires three strokes of the log splitter to do so.
Prior art mechanical log splitters frequently must have numerous exposed moving parts in addition to those components of the machine which actually effect the relative motion between a log and the cleaving blade. Such parts expose an operator, whose attention will naturally be focused upon the interaction of the cleaving blade and the log, to a great deal of danger. This is true even in the case where such additional moving parts are exposed only during a portion of the path of travel of the machinery of the device. Complex shrouds have been used to enclose such moving parts, but these needlessly increase the overall size and weight of the device. This is particularly true when the moving parts requiring enclosure would otherwise be exposed only during the extremes of their lines of travel.
Due to the great pressures required in mechanical log splitters, severe wear on contacting faces of moving parts is quite common. This in turn necessitates substantial down time for repairs. Many known mechanical log splitters only exacerbate this difficulty by failing to provide for ready disassembly of the machinery involved to replace parts most likely to fail.
Many mechanical log splitter designs have attempted to compensate for the problems of excessive jamming by employing extremely powerful activation means. The additional power provided is really useful only during initial cleaving blade penetration and is not utilized during the rest of the travel of the moving parts. Additional power, however, greatly increases the problem of wear. Rollers or bearings have been employed to counteract wear, but these dramatically increase the cost of manufacturing a piece of machinery which would otherwise be relatively inexpensive.